LISTEN TO HIM!
I work in a shop that would cost you 20+the price of the stud.
go to a Industrial store that sells nuts and bolts like Brofasco,i think thats how its spelled and get a grade 6-7stud.
grade 8 may be to brittle and the vibration from the motor will cause the bolt to snap when your taking it out.(brittle)
When buying the stud see if they have one with an allen key cut at the end. this is much easier to work with.
match the diameter of the Existing studs to match the your getting(bring a stud with you /cylinder
after you have your parts!
go to a machine shop and they will know what to do.
dont let them ripp you off to much.